1. Field of the Invention
The present invention relates to a power supply device and a battery module thereof. In particular, the present invention relates to a power supply device and a battery module thereof, in which a standby power supply unit and a primary power supply unit are separated from each other.
2. Description of Prior Art
Electric cylinder is a mechanical linear actuator, which is widely used in controlling the elevation and inclination of a sickbed. More specifically, a plurality of linear actuators is mounted to a sickbed. All the linear actuators are electrically connected to a control box. The control box sends control signals to each linear actuator to control the action of the linear actuator. A common control box for the linear actuator comprises a control circuit board and a standby power control circuit board. Thus, even a user does not want to buy a standby battery, the user cannot but buy the standby power control circuit board. The fact that the standby power control circuit board is provided in the control box not only increases the production cost for the manufacturers of the control box, but also raises the expense of buying such a control box for those who need not to use a battery.
In order to solve this problem, the power control circuit board is externally attached to the battery instead of being provided in the battery. However, a hydrogen-acid battery used in the control box may generate hydrogen and oxygen when it is charged. If the thus-generated gas contacts the power control circuit board, a short circuit will be generated on the power control circuit board to thereby catch fire.